Wheel

ABSTRACT

A wheel includes a rim having inner and outer flanges. A first end of each flange is positioned axially outwardly relative to the second end. A pair of bead seats are positioned one adjacent each flange, and each has an axially outer end connected to a second end of its flange by a flange connecting portion, and an axially inner end connected to one of a pair of side parts. Each side part is positioned between a central well and one of the inner and outer flanges, and connected to the well by a well connecting portion. The outer end of each bead seat is positioned radially outwardly relative to bead seat inner end. At least one of the flanges includes an extended portion which extends radially inwardly, such that a free end of the extended portion is positioned radially inwardly relative to the first end of the respective flange.

DESCRIPTION OF INVENTION

This invention relates to a wheel construction, in particular, but notexclusively to a wheel construction for agricultural vehicles orconstruction machines and the like.

Wheel constructions for agricultural vehicles and some other off-roadvehicles, are known which include a substantially circular rim havingaxially inner and axially outer flanges, each of which is positionedadjacent a respective bead seat, which provides a seat for a tyre beadof a tyre, which is fitted to a radially outer or “tyre side” of therim. Such wheel constructions typically also include a disc which isconnected to a radially inner side of the rim. The disc enables thewheel to be securable to a hub of a vehicle, for example by the use ofbolts. The rim and the disc may be separable from one another, or may bepermanently joined to one another, for example by welding.

The disc is connected to the rim in a central portion or ‘well’ of therim. The well is positioned between the inner and outer flanges, and maybe positioned substantially centrally between the inner and outerflanges. This well will hereinafter be referred to as the central well,despite the fact that the well need not be positioned exactly centrallybetween the inner and outer flanges. Each bead seat is positionedaxially inwardly of the respective flange, Each bead seat includes asubstantially straight surface against which a tyre bead is located.Upon inflation of the tyre to its in use pressure, a force is applied toeach bead seat and to each flange. Each bead seat has an axially outerend which is attached to the respective flange by a connecting part.Each flange connecting part is a concave portion, and is known in theart as a bead seat radius.

Between each bead seat and the central well is positioned a side part.It is known for the side part to include concave and convex portions,which create ‘sub-wells’ to form an ‘undulating’ side part, for example.Each side part is connected to the central well by a respectiveconnecting part. Each of these connecting parts is a concave portion,and will hereinafter be referred to as a well radius. Internationallyaccepted industry standards, for example the current European Tyre andRim Technical Organisation (ETRTO) standard, set out certain aspects ofwheel design, and criteria which wheel constructions should meet.

It is desirable for tyres to be inflated to a pressure which is as lowas possible for a given application, whilst preferably still being ableto bear the same load as when inflated to standard pressure for a tyreof the same circumference. Running at a lower air pressure typicallyimproves traction and compaction. For example, Michelin North Americaoffers ‘Improved Flexion’ tyres, which are able to bear the same load asa standard tyre of the same rolling circumference, at up to 20% lowerair pressure, or are able to bear up to 20% more load than a standardtyre of the same rolling circumference, at standard air pressure.

A disadvantage of running at relatively low air pressures is that it iscommon for tyres inflated to relatively low pressures to slip relativeto the rim. A disadvantage of relatively stiff tyres is that they can beawkward to fit to a rim. The advantages of higher traction and reducedcompaction provided by running tyres at relatively low pressures can beoffset by these disadvantages.

It is an aim of the present invention to ameliorate one or moredisadvantages experienced by users of known rims.

According to the present invention, there is provided a wheelconstruction including a rim, the rim having an inner flange and anouter flange, each of the inner flange and the outer flange having afirst end and a second end, the first end of each of the inner and outerflange being positioned axially outwardly relative to the second end ofthe respective flange, the rim further including a central wellpositioned between the inner flange and the outer flange, a pair of beadseats, one being positioned adjacent each flange, each bead seat havingan axially outer end which is connected to a second end of therespective flange by a flange connecting portion, and an axially innerend which is connected to one of a pair of side parts, each side partbeing positioned between the central well and one of the inner flangeand outer flange, and connected to the central well by a well connectingportion, the axially outer end of each bead seat being positionedradially outwardly relative to the axially inner end of the respectivebead seat, wherein at least one of the inner flange and the outer flangeincludes an extended portion which extends radially inwardly, such thata free end of the extended portion is positioned radially inwardlyrelative to the first end of the respective flange, and wherein at leastone of the side parts includes a substantially straight portion and acurved portion, a first end of the straight portion being positionedadjacent the respective bead seat, and connected to the respective beadseat by a curved connecting portion, and a second end of the straightportion being connected to the curved portion of the side part by afirst substantially concave surface to provide a first sub-well, and thecurved portion of the side part including a second sub-well, which isdefined by a pair of convex surfaces, separated by a second concavesurface.

Each flange connecting portion may include a substantially concavesurface.

Each flange connecting portion may include a substantially straightsurface.

The extended portion may be substantially straight.

The radial extent of the extended portion may be substantially equal tothe radial extent of the respective flange connecting portion.

At least one of the flanges may include a convex surface.

The free end of the or each extended portion may lie axially outwardlyrelative to the radial peak of the convex surface of the respectiveflange.

The free end of the or each extended portion may lie substantiallyaxially aligned with the first end of the respective flange.

The free end of the or each extended portion may lie substantiallyaxially outwardly relative to the first end of the respective flange.

The free end of the or each extended portion may lie axially inwardlyrelative to a radial peak of the convex surface of the respectiveflange.

The free end of the or each extended portion may lie axially inwardlyrelative to the first end of the respective flange.

At least one of the well connecting portions may include a concavesurface.

The pair of side parts may be substantially identical to one another,albeit a mirror image of one another about a substantially radiallyextending plane.

The rim may be substantially symmetrical.

At least one of the curved connecting portions which connects each beadseat to the adjacent side part may include a concave surface.

The wheel construction may further include a disc which is attachable tothe rim.

According to a second aspect of the invention, there is provided avehicle including a wheel construction according to any of the precedingclaims.

The present invention will now be described by way of example only, withreference to the accompanying drawings, of which:

FIG. 1 is a perspective view of a wheel construction;

FIG. 2A is a cross-sectional view of a part of the wheel rim of FIG. 1;and

FIG. 2B an enlarged view of a part of FIG. 2A as indicated by dottedlines in FIG. 2A.

Referring to the figures, there is shown a wheel construction 10 whichincludes a rim 12. The wheel construction 10 also includes a disc 14which is connected to the rim 12. In the example shown, the disc 14 ispermanently connected to the rim 12, for example by welding, but it willbe appreciated that the disc 14 may, alternatively, be detachable fromthe rim 12. The disc 14 enables the wheel construction 10 to be attachedto a hub or an axle of a vehicle. Features of the disc 14, for exampleits shape and attachment formations, are typical in nature. It will beappreciated that other forms of disc 14 may be suitable and appropriate.

The rim 12 is substantially circular, having a radially outer surface 12a (commonly referred to as a tyre-side 12 a), upon which, in use, a tyreis fitted, and a radially inner surface 12 b (commonly referred to as aweather side 12 b), to a part of which the disc 14 is attached. The rimhas an axis A, which is substantially central. When used herein, theterm ‘axial’ is defined as being generally parallel to the axis A (shownas a dashed line in FIG. 1). When used herein, the term ‘radial’ isdefined as being generally perpendicular to the central axis A. Theterms ‘inwardly’ and outwardly' when used herein are used to describeaxial positions, with ‘inwardly’ meaning closer to an axially centralplane, and ‘outwardly’ meaning further from the axially central plane B(shown by a dashed line in FIG. 2A.

The rim 12 includes an inner flange 16, an outer flange 18, and acentral well 20 positioned between the inner flange 16 and the outerflange 18. Each flange has a first end 16 a, 18 a, and a second end 16b, 18 b. In an embodiment, at least one of the inner flange 16 and theouter flange 18 includes a convex surface 13, 15, i.e. the or eachflange 16, 18 has an externally radiused portion on the tyre side 12 a.The radius of curvature of the convex surface 13, 15 of the or eachflange 16, 18 may be approximately 15 mm±2 mm. A peak of the convexsurface 13, 15 of at least one of the flanges 16, 18 may define thegreatest radial extent of the rim 12. Each flange 16, 18 has an axiallength L_(F).

The central well 20 is a substantially cylindrical portion of the rim12, with both its tyre side and its inner surface being substantiallystraight in cross section. The central well 20 may have a substantiallyconstant radius along its whole axial extent.

The rim 12 also includes a pair of bead seats 22, 24, one beingpositioned adjacent each flange 16, 18. Each bead seat 22, 24 has afirst end 22 a, 24 a, which is connected to the second end 16 b, 18 b ofthe respective flange 16, 18 by a respective flange connecting portion26, 28, and a second end 22 b, 24 b which is connected to one of a pairof side parts 30, 32, of the rim 12. The first end 22 a, 24 a of eachbead seat 22, 24 is located axially outwardly relative to the respectivesecond end 22 b, 24 b. The first, axially outer end 22 a, 24 a ispositioned radially outwardly relative to the respective second, axiallyinner end 22 b, 24 b. The tyre side and inner surface of each bead seat22, 24 are substantially straight in cross-section, such that each beadseat 22, 24 is substantially frustoconical.

The or each flange connection portion 26, 28 has a first end 26 a, 28 a,which is adjacent the second end 16 b, 18 b of the respective flange 16,18, and a second end 26 b, 28 b which is adjacent the respective beadseat 22, 24. The or each flange connection portion 26, 28 includes aconcave surface, i.e. the tyre side of the or each flange connectionportion 26, 28 is internally radiused. The radius of curvature of theconcave surface of the or each flange connection portion 26, 28 may beapproximately 8 mm. The or each flange connection portion 26, 28 mayalso include a substantially straight surface 27, 29, on its tyre side,at least. In such an embodiment, the concave surface is positioned atthe second end 26 b, 28 b, adjacent with and joining the respective beadseat 22, 24, and the respective substantially straight surface 27, 29 ispositioned at the first end 26 a, 28 a, adjacent and joining with therespective flange 16, 18. The straight surface 27, 29 of the or eachflange connection portion 26, 28 may extend in a substantially radialdirection. The radial length of the substantially straight surface 27,29 of the or each flange connection portion 26, 28 may be betweenapproximately 1 mm and 10 mm, and may be approximately 2.5 mm orapproximately 6 mm, depending upon the overall size of the wheel.

The rim 12 includes a pair of side parts 30, 32, each being positionedbetween the central well 20 and one of the inner flange 16 and outerflange 18. Each side part 30, 32 is connected to the central well 20 bya respective well connecting portion 34, 36. In an embodiment, at leastone of the well connecting portions 34, 36 includes a concave surface,i.e. the tyre side of the or each well connecting portion 34, 36includes an internally radiused surface. Both well connecting portions34, 36 may include a concave surface. The radius of curvature of the oreach well connecting portion 34, 36 may be approximately 15 mm±2 mm.

At least one of the side parts 30, 32 includes a substantially straightportion 38, 40 and a curved portion 42, 44. A first end 38 a, 40 a ofthe or each straight portion 38, 40 is positioned adjacent therespective bead seat 22, 24, and is connected to the second end 22 b, 24b of the respective bead seat 22, 24 by a curved connecting portion 46,48. The or each curved connecting portion 46, 48 may include a convexsurface, i.e. the tyre side of the or each curved connecting portion 46,48 may be externally radiused. The radius of curvature of the curvedconnecting portion 46, 48 may be 16 mm±2 mm. A second end 38 b, 40 b ofthe or each straight portion 38, 40 is connected to the respectivecurved portion 42, 44 of the side part 30, 32 by a first substantiallyconcave surface 50, 52, i.e. the tyre side of first substantiallyconcave surface may be internally radiused. The radius of curvature ofthe or each first substantially concave surface 50, 52 may be 15 mm-±2mm. The first substantially concave surface 50, 52 provides a first‘sub-well’, positioned between the central well 20 and the respectivebead seat 22, 24.

The curved portion 42, 44 of one or both of the side parts 30, 32 mayinclude a second sub-well 54, 56, which is defined by a pair of convexsurfaces 58, 60, 62, 64, separated by a second concave surface 66, 68.The tyre side of each of the convex surfaces 58, 60, 62, 64 includes anexternally radiused portion, and the tyre side of each of the secondconcave surfaces 66, 68 includes an internally radiused portion. Theradius of curvature of each convex surface 58, 60, 62, 64 may beapproximately 16 mm±2 mm. The radius of curvature of the or each secondconcave surface 66, 68 may be 15 mm±2 mm. It will be appreciated thatone or both of the side parts 30, 32 may be provided with a secondsub-well 54, 56.

At least one of the inner flange 16 and the outer flange 18 includes anextended portion 17, 19 which extends radially inwardly from the first(axially outward) end 16 a, 18 a of the respective flange 16, 18, suchthat at least a part of a free end 17 a, 19 a of the or each extendedportion 17, 19 is positioned radially inwardly relative to the secondend 16 b, 18 b, of the respective flange 16, 18. The or each extendedportion 17, 19 may include a substantially straight surface, and may besubstantially straight along its entire length. The or each extendedportion 17, 19 extends in a generally radially inward direction.

The free end 17 a, 19 a of the or each extended portion may lie axiallyoutwardly relative to the radial peak of the convex surface 13, 15 ofthe respective flange 16, 18. It will be appreciated that even if the oreach flange 16, 18 does not include a convex surface, the free end 17 a,19 a of the or each extended portion 17, 19 may extend axially outwardlyfrom a most radially outwardly positioned portion of the respectiveflange 16, 18. The or each free end 17 a, 19 a may lie substantiallyaxially aligned with the first end 16 a, 18 a of the respective flange16, 18 or may lie substantially axially outwardly relative to the firstend 16 a, 18 a of the respective flange 16, 18.

Alternatively, The free end 17 a, 19 a of the or each extended portion17, 19 may lie axially inwardly relative to the radial peak of theconvex surface 13, 15 of the respective flange 16, 18, or where therespective flange does not include a convex surface, the free end 17 a,19 a of the or each extended portion 17, 19 may lie axially inwardlyrelative to a most radially outwardly positioned portion of therespective flange 16, 18.

The free end 17 a, 19 a of the or each extended portion 17, 19 may havea substantially flat end face 17 c, 19 c. The or each end face 17 c, 19c may be substantially parallel with the respective bead seat 22, 24. Anangle β between the or each face 17 c, 19 c, and a plane E which isparallel to the axis A of the rim 12 may be between 0° and 45° and ispreferably between 0° and 10°, and more preferably between approximately4° and 6° and may be approximately 5°. This is illustrated in FIG. 2Ewhich shows a cross-section through the rim 12, taken through a planewhich extends substantially radially, from the axis A in a single radialdirection. In FIG. 2B, the angle β is the angle subtended above theplane E. It will be appreciated that the orientation of the or each endface 17 c, 19 c may be such that the angle β is subtended below theplane E, and may be given a ‘−’ (minus or negative) notation. In otherwords, the angle β may be between 0° and approximately ±45°, morepreferably between 0° and approximately 10°, and is more preferablyapproximately ±5°. The angle β will tend to be ‘negative’, i.e.subtended below the plane E, in an embodiment where the free end 17 a,19 a of the or each extended portion 17, 19 is positioned radiallyinwardly relative to the axially inwardly relative to the most radiallyoutwardly positioned portion of the respective flange 16, 18 or theradial peak of the convex surface 13, 15 of the respective flange 16,18.

The angle α between the bead seat 22 and the plane E which is parallelto the axis A is approximately 5°±1°.

The or each extended portion 17, 19 may extend the respective flange 16,18 radially beyond the radial position of the first end 22 a of therespective bead seat 22, 24. The or each end face 17 c, 19 c may besubstantially parallel with the respective bead seat 22, 24. The lengthof the or each extended portion 17, 19 may be between approximately 0.1mm and approximately 15 mm and may be 12 mm, for example.

Knurling may be provided on the tyre side 12 a of the rim 12. Forexample, knurling may be provided on at least a part of at least one ofthe bead seats 22, 24. Standard knurling, which is typically used in theart is preferable to a relatively high amount of knurling, or deepknurling, as this reduces the likelihood of damage to the tyre in theevent that the tyre slips circumferentially relative to the rim duringfitting or during driving of a vehicle to which the rim 12 and thecorresponding tyre are fitted. The combination of the extended portions17, 19 in combination with the shape of the profile of the rim, inparticular the shape of the or each side part 30, 32 avoids the need toprovide additional and/or deep knurling to achieve reduced incidences oftyre slippage compared to known rim profiles.

The examples of sizes, including lengths and radii, provided in thisspecification are in relation to a rim 12 having a nominal rim width Wof approximately 762 mm. It will be appreciated that corresponding sizesfor rims 12 of differing nominal widths may have to be factoredappropriately.

The invention, in particular the profile of the or each side part 30, 32of the rim 12, facilitates the tyre mounting process, particularly onhigh load capacity tyres and/or low pressure tyres, which typically havestiff tyre walls, which reduces the risk of damage to the tyre duringfitting on the rim 12.

When a tyre which is being fitted to the rim 12 is inflated, during themounting process, a low pressure is used, for safety reasons. Theprofile of the rim 12, particularly the features of the or each sidepart 30, 32, facilitates movement of a bead of the tyre in a generallyaxial direction towards each bead seat 22, 24, and inhibits the or eachbead of the tyre from ‘sticking’ on the respective side part 30, 32. Theprofile of the rim 12, in particular the shape of the or each side part30, 32 reduces stress in the rim 12.

The profile of the rim 12, in particular the extended portions 17, 19 ofthe or each flange 16, 18 provides increased stiffness of the rim 12,particularly in the region of the rim 12 near to the or each flange 16,18. The increased stiffness of the rim 12 means that the rim 12 is lesslikely to yield under the load of the tyre, making the rim 12advantageous for high load capacity applications, which typicallyrequire stiffer tyres. The increased stiffness, and lower likelihood ofyielding leads to increased surface pressure between the rim 12 and thecorresponding tyre. In turn this leads to greater friction between therim 12 and the tyre, and less likelihood of slippage of the tyregenerally circumferentially relative to the rim 12.

The inclusion of the or each extended portion 17, 19 minimises, or atleast reduces shrinkage of the rim during tyre mounting and/orinflation. This provides a more consistent rim profile.

The rim 12 is particularly advantageous in reducing generallycircumferential slipping of a corresponding tyre relative to the rim 12for high traction, low pressure tyres. The profile of the rim 12, inparticular the shape of the of each side part 30, 32 is advantageous inthe mounting of relatively stiff, high load capacity tyres the use ofwhich is facilitated, at least in part, by the provision of the extendedportions 17, 19 of the or each flange 16, 18. The profile of the rimincluding three concave formations (i.e. wells) is that during fitting,a tyre is encouraged to slide directly to the well connecting portion34, 36 or ‘rim well’ and the risk of the tyre ‘sticking’ on the sidepart, particularly when mounting a second side of the tyre. This ensuresthat the full diagonal mounting distance is used, to reduce the risk ofdamaging the tyre.

When used in this specification and claims, the terms “comprises” and“comprising” and variations thereof mean that the specified features,steps or integers are included. The terms are not to be interpreted toexclude the presence of other features, steps or components.

The features disclosed in the foregoing description, or the followingclaims, or the accompanying drawings, expressed in their specific formsor in terms of a means for performing the disclosed function, or amethod or process for attaining the disclosed result, as appropriate,may, separately, or in any combination of such features, be utilised forrealising the invention in diverse forms thereof.

The invention claimed is:
 1. A wheel construction including a rim, therim having an inner flange and an outer flange, each of the inner flangeand the outer flange having a first end and a second end, the first endof each of the inner and outer flange being positioned axially outwardlyrelative to the second end of the respective flange, the rim furtherincluding a central well positioned between the inner flange and theouter flange, a pair of bead seats, one being positioned adjacent eachflange, each bead seat having an axially outer end which is connected tothe second end of the respective flange by a flange connecting portion,the flange connecting portion including a substantially concave surfaceand a substantially straight surface, said substantially straightsurface being adjacent to and adjoining the second end of the respectiveflange, and each bead seat also having an axially inner end which isconnected to one of a pair of side parts, each side part beingpositioned between the central well and one of the inner flange andouter flange, and connected to the central well by a well connectingportion, the axially outer end of each bead seat being positionedradially outwardly relative to the axially inner end of the respectivebead seat, wherein at least one of the inner flange and the outer flangeincludes an extended portion which extends radially inwardly, such thata free end of the extended portion is positioned radially inwardlyrelative to the first end and to the second end of the respectiveflange, wherein the radial extent of the or each extended portion issubstantially equal to the radial extent of the respective flangeconnecting portion, and wherein at least one of the side parts includesa substantially straight portion and a curved portion, a first end ofthe straight portion being positioned adjacent the respective bead seat,and connected to the respective bead seat by a curved connectingportion, and a second end of the straight portion being connected to thecurved portion of the side part by a first substantially concave surfaceto provide a first sub-well, and the curved portion of the side partincluding a second sub-well, which is defined by a pair of convexsurfaces, separated by a second concave surface.
 2. The wheelconstruction according to claim 1 wherein the extended portion issubstantially straight.
 3. The wheel construction according to claim 1wherein at least one of the flanges includes a convex surface.
 4. Thewheel construction according to claim 3 wherein the free end of the oreach extended portion lies axially outwardly relative to a radial peakof the convex surface of the respective flange.
 5. The wheelconstruction according to claim 1 wherein the free end of the or eachextended portion lies substantially axially aligned with the first endof the respective flange.
 6. The wheel construction according to claim 1wherein the free end of the or each extended portion lies substantiallyaxially outwardly relative to the first end of the respective flange. 7.The wheel construction according to claim 1 wherein at least one of thewell connecting portions includes a concave surface.
 8. The wheelconstruction according to claim 1 wherein the pair of side parts may bea mirror image of one another about a substantially radially extendingplane.
 9. The wheel constructions according to claim 1 wherein the rimis substantially symmetrical.
 10. The wheel construction according toclaim 1 wherein at least one of the curved connecting portions whichconnects each bead seat to the adjacent side part includes a concavesurface.
 11. The wheel construction according to claim 1, and furtherincluding a disc which is attachable to the rim.